The invention relates to a coolant circuit for an internal combustion engine comprising a compression machine for intake air, with the coolant circuit consisting of a high-temperature circuit and a low-temperature circuit, and with the high-temperature circuit being provided to cool the internal combustion engine by way of a coolant radiator and a first coolant pump arranged in the high-temperature circuit.
German unexamined patent application DE 41 04 093 A1 discloses a cooling system for vehicles with internal combustion engines, which includes a plurality of coolant circuits with associated heat exchangers that are designated as follows: the first heat exchanger cools the engine coolant, the second cools the engine lubricant, and the third cools the charge air. Temperature sensors are arranged in each coolant circuit and are connected to an electrical switching device. The switching device is connected to actuating elements that control the performance of the heat exchangers as a function of the signals from the temperature sensors. The cooling system is characterized in that a first control unit is provided which includes at least one microprocessor and determines the required cooling energy demand of the individual coolant circuits as a function of the signals from the temperature sensors, and in that actuating elements are assigned to each of the coolant circuits to individually influence the performance of the respective heat exchanger.
The known prior art has the disadvantage that parasitic heat flow from the engine compartment of the vehicle and from an exhaust turbocharger heats up the low-temperature circuit even under low load conditions. This results in an excessive temperature level in each temperature circuit. The result is excessive energy consumption, including in the air conditioning system that controls the temperature in a passenger compartment.
The object of the present invention is to provide a measure to avoid the afore-mentioned disadvantages.
This and other objects are achieved according to the invention by providing a completely separate low-temperature circuit from the high-temperature circuit, with the intercooler and the condenser being arranged in the low-temperature circuit.
This results in a complete separation of the high-temperature circuit for the coolant that cools the internal combustion engine from the low-temperature circuit that indirectly cools the charge air and air conditions a passenger compartment.
According to a further development of the invention, the intercooler and the condenser are preferably arranged in parallel in the low-temperature circuit, e.g. the coolant flows in parallel through both.
Further, a first valve is arranged upstream of the intercooler in the direction of flow of a coolant, and/or a second valve is located upstream of the condenser. This results in several advantageous synergy effects, which is shown in a table below. In a further example of an embodiment, the valves may also be located downstream of the intercooler and/or the condenser, or an intermix of said arrangements.
Preferably, the valves are operated in a regulated or controlled fashion.
Furthermore, the second coolant pump is preferably operated at a speed that meets the operating conditions so as to ensure optimal efficiency.
With the coolant circuit according to the invention for an internal combustion engine, the following operating situations can then be described advantageously as a function of the operating condition of the internal combustion engine (ICE):
OperatingSecondpointcoolantFirstSecondof the ICE:pump:valve:valve:Comment:e.g.: at idlecontrolled closedopenHigh demand for air byconditioning at idle, for demandexample during stop-and-go traffic at high outside air temperature. In this case, increase of the coolant flow over the condenser, and reduction of the cooling of the charge air, or valve timing, if applicable.e.g.: Max. controlled openclosedHigh demand on charge air load on a bycooling with simultaneously restricteddemandlow air conditioning demand, access such as during moderate highwayoutside temperatures and high [Autobahn]demand driving (e.g. restricted access highway, dynamic mountain driving)Max. aircontrolled openopenHigh demand driving resulting conditioning byin high cooling need of the and max. demandintercooler. Simultaneously load of high outside air temperature internaland high air conditioning combustiondemand.engine
Due to the design of the cooling circuit according to the invention, parasitic heat intake is reduced and, therefore, the thermal base load of the low-temperature cooling circuit is reduced. This leads to a reduction of the pressure level in the refrigeration cycle, which results in a positive reduction of the total energy consumption.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawing.